Update CV_MAJOR_VERSION == 3 to >= 3.0. (#139)

CMakeLists.txt

FrameProcessor.cpp

FrameProcessor.h

gui_qt/mainwindow.cpp

package_bgs/MixtureOfGaussianV2.cpp

package_bgs/MixtureOfGaussianV2.h

wrapper_java/bgslibrary_java_module.cpp

wrapper_matlab/backgroundSubtractor_wrapper.cpp

wrapper_python/bgslibrary_module.cpp